Is freeware, multi-lingual and the website says it is allowed to be used in commercial environments too. Donations are accepted. This text editor has support for regex and I tested (previous versions of) the software with 2GByte log files and search/replace actions in those files were fast on a 7 year old PC (16GB RAM, i5 CPU (3th generation, 3.5GHz)).

Caveats:- Regex I haven't played with, so how well/functional the support is I can't tell. - Haven't tested with log files bigger than 2GByte, so if 20GByte log files can be processed, I can't tell.

Well, you could just buy EmEditor, it's not that expensive, or EditPad Pro, that does also handle really big files with ease.

For a freebee, check out the really old, and a bit harsh to download, MadEdit, it opened a > 20GB file without a hitch, and supports regex search and replace.

Like I suggested above, and me and others before, it would really get you more helpful answers if you specify what you want, need and desire complete instead of letting us pull those details with pliers, in the dark